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Law enforcement agencies across the UK successfully lobbied to use a facial recognition system known to be discriminatory against women, young people, and individuals from ethnic minority groups, after complaining that a less biased version produced fewer investigative leads.

How the System Works

British police utilize the national police database to conduct searches using historical face recognition. This procedure involves matching a reference photograph of a person of interest against a database of more than 19 million mugshots to identify potential matches.

Admitted Bias

The UK interior ministry conceded last week that the technology was flawed. This acknowledgment followed a study by the National Physical Laboratory (NPL) found it incorrectly matched Black and Asian people and women at significantly higher rates than Caucasian males. The Home Office said it “had acted on the findings”.

“This raises the question of whether this technology only becomes useful if users tolerate biases in race and sex. Convenience is a poor argument for overriding fundamental rights.”

Known Issue

Internal documents show that this bias has been recognized for over twelve months. Furthermore, police forces argued to overturn an initial decision that was designed to mitigate the problem.

Police bosses were notified of the algorithmic discrimination in late 2024. The Home Office-commissioned laboratory study concluded the system was had a higher probability to suggest incorrect matches for photos of women, individuals of Black ethnicity, and those under 40 years old.

A Policy U-Turn

In response, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for possible hits be increased to a point where the bias was significantly reduced.

However, this directive was reversed the following month following complaints from police that the modified technology was producing a lower number of “investigative leads”. Internal records show the higher threshold cut the number of searches resulting in potential matches from 56% to a mere 14%.

Profound Inequalities

Although the Home Office and NPCC refused to say what threshold is now in operation, the latest independent review discovered the system could produce false positives for women of Black heritage almost 100 times more often than for white women at certain settings.

The ministry commented on these results: “Our evaluation identified that in a specific scenarios the software is has a greater tendency to incorrectly include some demographic groups in its match reports.”

Operational Effectiveness vs. Bias

Describing the effect of the temporary raise to the system's confidence threshold, the police records note: “The change significantly reduces the impact of bias across legally safeguarded attributes of race, generation and gender but had a substantially detrimental effect on police efficiency”. The documents add that police units complained that “a previously useful tool now delivered outcomes of limited benefit”.

Broader Rollout Plans

Meanwhile, the UK administration has opened a ten-week public review on its plans to widen the use of biometric scanning systems. Policing minister Sarah Jones has described the tool as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the national policing equality strategy, said: “There was very little consideration in race action plan meetings of the technology deployment even with clear relevance with the plan’s concerns.

“This disclosure show once again that the anti-racism commitments policing has undertaken through the equality initiative are not being translated into broader operations. Our reports have warned that innovative tools are being rolled out in a landscape where ethnic inequalities, weak scrutiny and faulty information gathering already persist.

“Any use of this technology must adhere to rigorous official guidelines, be subject to external review, and demonstrate it reduces rather than compounds ethnic bias.”

Home Office Response

A Home Office spokesperson stated: “The Home Office takes the findings of the report with utmost gravity and we have implemented changes. A new algorithm has been independently tested and acquired, which has demonstrated no measurable discrimination. It will be trialled in the coming months and will be undergo evaluation.

“The foremost aim is protecting the public. This gamechanging technology will assist officers to put criminals and rapists behind bars. There is human involvement in every step of the procedure and no further action would be pursued without trained officers meticulously examining the output.”